State Water Resources Research Institute Program

Project ID: 2010VA142G

Title: Denitrifying bacterial community structure and diversity, and denitrification potential as affected by hydrologic design and soil properties in wetlands created in Chesapeake Piedmont, USA

Project Type: Research

Start Date: 9/01/2010

End Date: 8/31/2011

Congressional District: VA-11

Focus Categories: Wetlands, Water Quality, Hydrogeochemistry

Keywords: Denitrification, created wetlands, wetland function, hydrologic connectivity, denitrifying bacterial community, wetland soil

Principal Investigator: Ahn, Changwoo (George Mason University)

Federal Funds: $ 60,396.

Non-Federal Matching Federal Funds: $ 60,402

Abstract Wetland creation is a common practice for compensatory mitigation. Unfortunately, created wetlands often fail to support biotic communities comparable to those in similar, naturally occurring wetlands. Soil parameters in created wetlands are often found not indicative of "hydric soils" typical of natural wetlands, that support important biogeochemical functions. Denitrification is one of the key biogeochemical functions of natural wetlands and denitrifying bacteria play a significant role in it due to their ability to convert nitrate to gaseous N2, but little has been known about the role of bacterial community composition in the process. Moreover,there are currently no specific methods and/or designs that would enhance the development of the biogeochemical function in created wetlands. The objective of this study is to investigate the influence of hydro-connectivity (HC) as a design element on denitrification potential (DP), and denitrifying bacterial community structure and diversity in created wetlands. It is hypothesized that wetlands created with greater HC would better support developments in bacterial communities (e.g., denitrifiers) and in biogeochemical functions (e.g., denitrification). Bacterial community composition and diversity data will serve as a surrogate measure for the development of a denitrification function as affected by soil properties that may vary by the age of site. We will attempt to establish a quantitative relationship and/or association between structural (i.e., denitrifying bacterial community diversity) and functional measures (i.e., DP), which will help us evaluate functional development in wetlands created to mitigate the loss of natural wetlands. The study will be conducted in three mitigation wetlands with varying ages, all created in the Piedmont region of Virginia. The project uniquely combines biogeochemistry, molecular microbial ecology, and ecological engineering (i.e., design criteria for creating/restoring wetlands). The study is field based with extensive lab analyses involved for denitrification potential, soil physicochemistry and bacterial community.

The outcome of the study will provide useful information on how HC and soil properties influence denitrifying bacterial community composition in relation to denitrification function of created wetlands. The expected results will also reveal how a design element (i.e., HC) are associated with functional (i.e., denitrification) aspects of ecosystem development in created wetlands, thus guiding wetland managers and/or engineers for future efforts in wetland creation and restoration throughout agricultural and urban watersheds in the nation.

Progress/Completion Report, 2010, PDF
Progress/Completion Report, 2011, PDF

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